Predictive coding techniques may include resampling of reference pictures, where various coding parameters are determined based on the resolution(s) or pixel format(s) of the prediction references. In a first aspect, lists of weights for use in weighted prediction are based on the resolution(s) of prediction references. In a second aspect, resampling filter parameters are selected based on the resolutions of prediction references. In a third aspect, deblocking filter parameters are based on the resolution(s) of prediction references.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An image processing method, comprising: decoding reference picture(s) having corresponding reference resolution(s); determining prediction weight(s) for the reference picture(s) based on the corresponding reference resolutions(s); resampling the decoded reference picture(s); and predicting a portion of a current image based on the resampled reference picture(s) and the prediction weight(s).
2. The method of claim 1 , wherein: the predicting is multihypothesis prediction with two reference pictures; and the prediction weights depend on the difference in resolution of the two reference pictures.
3. The method of claim 2 , wherein, a first prediction weight is determined for a first reference picture having a first resolution; and a second prediction weight, lower than the first prediction weight, is determined for a second reference picture having a second resolution lower than the first resolution.
4. The method of claim 1 , wherein, when at least one of the corresponding reference resolutions is smaller than a current resolution of the current image, then all the prediction weights are determined to be the same weight.
5. The method of claim 1 , wherein the prediction weights for the reference picture(s) are determined by selecting an entry from a list of prediction weights, and wherein the prediction weights are encoded in a bitstream along with an indication of the relative probabilities of the weights in the list of prediction weights.
6. The method of claim 1 , wherein the prediction weights for the reference picture(s) are determined by selecting an entry from a list of prediction weights based on the corresponding reference resolution(s).
7. The method of claim 1 , wherein the prediction weights for the reference picture(s) are determined by selecting an entry from a list of prediction weights, and the list of prediction weights is selected from a plurality of lists of weights based on the corresponding reference resolution(s).
8. The method of claim 1 , wherein the prediction reference(s) are classified as based on whether their corresponding reference resolutions(s) are larger or smaller than a current resolution of the current image; and the prediction weights for the reference picture(s) are determined based on the classification(s).
9. A system for image processing, comprising: a decoder for decoding reference pictures having corresponding reference resolution(s); a reference picture buffer storing the decoded reference pictures; a resampler for resampling reference pictures from the reference picture buffer; a controller for prediction weight(s) for the reference picture(s) based on the corresponding reference resolution(s); and a predictor for predicting a current image based on the resampled reference pictures and the prediction weights.
10. The system of claim 9 , wherein: the predicting is multihypothesis prediction with two reference pictures; the prediction weights depend on the difference in resolution of the two reference pictures; a first prediction weight is determined for a first reference picture having a first resolution; and a second prediction weight, lower than the first prediction weight, is determined for a second reference picture having a second resolution lower than the first resolution.
11. A non-transitory computer readable medium having instructions that, when executed by a processor, cause: decoding reference picture(s) having corresponding reference resolution(s); determining prediction weight(s) for the reference picture(s) based on the corresponding reference resolution(s); resampling the decoded reference picture(s); and predicting a portion of a current image based on the resampled reference picture(s) and the prediction weight(s).
12. The medium of claim 11 , wherein: the predicting is multihypothesis prediction with two reference pictures; the prediction weights depend on the difference in resolution of the two reference pictures; a first prediction weight is determined for a first reference picture having a first resolution; and a second prediction weight, lower than the first prediction weight, is determined for a second reference picture having a second resolution lower than the first resolution.
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February 24, 2020
May 17, 2022
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